ISLAMABAD, Pakistan (CNN) -- Violence flared in northwestern Pakistan for a third straight day Sunday as one anti-Taliban government leader was killed and another survived an attack, officials said.

Pro-government tribal leader Malik Sher Zai was killed early Sunday north of Peshawar, Pakistan, in the Bajaur Agency federally administered tribal region, political administration official Abdul Malik told CNN. His house was also completely destroyed in the incident, Malik said.

Also Sunday, gunmen opened fire on the reception area of anti-Taliban mayor Fahim-ur-Rehman in Peshawar, a police official told CNN. He was unhurt, and his security staff managed to kill three militants while the rest fled, the official said. Efforts to identify the three have so far been unsuccessful, police said.

In Peshawar on Saturday, a suicide car bomber blew himself up at a police checkpoint, killing 11 people and wounding 26. Shafi Ullah, deputy superintendent of police, said authorities had stopped the bomber at the post when the explosion occurred, killing three women, three children, a police officer and four other men.

The blast occurred in the Pushtakhara neighborhood, said Peshawar police officer Idress Khan. Some 50 to 60 kilograms of explosives were used in the bomb, he said.

Peshawar is the capital of Pakistan's North West Frontier Province. It has repeatedly come under attack in recent days. Intelligence officials said the attacks are retaliation against an army offensive to rout militants from their havens along the border with Afghanistan. Peshawar is about 120 kilometers (75 miles) northwest of the Pakistani capital, Islamabad.

On Sunday, the Pakistan military reported it had killed more than 20 militants in South Waziristan and the Swat Valley. Twenty-five houses in the village of Kam Narakai in the South Waziristan were searched as part of the ongoing military operations, and three improvised explosive devices (IEDs) were defused, the military said in a statement. A bridge in South Waziristan was cleared and four other IEDs were neutralized, the statement said.

No one claimed responsibility for Saturday's blast. However, Taliban senior commander Qari Hussain said Saturday that the Taliban claimed responsibility for dual bombings Friday that killed at least 17 people, including security officials, in Peshawar.

Journalists Nasir Dawar and Umar Aziz Khan contributed to this report for CNN.